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The tuatara, Sphenodon punctatus, a nocturnal
reptile, is one of New Zealand's most unique animals. All
other living reptiles are classified into three orders, but
the tuatara is the only surviving representative of an
otherwise extinct order of “beak-headed” reptiles, the
Rhynchocephalia, which lived some 200 million years
ago in Asia, Africa, Europe, and North America, and became
extinct more than 100 million years ago.

The tuatara closely resembles some lizards in appearance,
but, despite the superficial similarity, certain skeletal and
anatomical features distinguish the tuatara from the lizards.
The tuatara reaches a length of almost 2 ft, and has a
lizard-shaped body with a crest of softish spines forming a
midrow along the back of the head, and a row of smaller
spines along the middle of the back. The spines, the skin
folds of the neck, and the total weight and length all reach
greater sizes in males than females. Adult males weigh up to
1,000 grams, almost twice the weight reached by females. The
animal is usually an olive-green colour but specimens vary
from slate grey to almost brick red and all have the
background colour broken by numerous small lighter spots. The
well-developed pineal organ, or so-called “third eye”,
prominent in the young tuatara, is also found in lizards. So
far as is known it does not function as a light receptor.

Once the tuatara inhabited the mainland of New Zealand but
is now found only on 20 small exposed islands which are
covered to some extent by scrub or low coastal forest. One
group of islands is in Cook Strait, the others lie off the
North Island between North Cape and East Cape. The tuataras
make burrows in loose soil or use the burrows of sea birds
such as prions, shearwaters, and diving petrels, and may even
share burrows with birds incubating eggs or rearing
chicks.

Mating is believed to occur in January, and between
October and December the females lay from eight to 15 oval
eggs in a clutch at the bottom of a shallow excavation about
5 in. deep. The parent abandons the eggs after covering them
with earth. Some 15 months later the young cut their way
through the flexible parchment-like shell of the egg with the
small temporary “egg breaker” at the tip of the snout. The
earth-coloured young then butt their way through the soil to
the surface where they seek cover in rock crevices, under
logs, or in small burrows which they excavate for themselves.
Tuataras only become sexually mature after about 20 years of
growth, and continue to grow slowly all their lives. Very
large tuataras could be more than a century old, for the
tuatara has one of the slowest rates of growth of any
reptile.

Young tuataras feed readily on small ground animals, such
as earthworms and small insects. Adults forage for wetas
(wingless crickets), beetles, snails, and, occasionally, the
eggs and young of petrels. As most of the islands lack
streams or pools, tuataras probably get most of their water
from their food or dew. Tuataras are active at night,
remaining active in temperatures as low as 7°c and they can
tolerate high temperatures for brief periods. W. H. Dawbin
(1962) gives a detailed account of the life history and
habits of the tuatara based on extensive field
observations.

The New Zealand Government rigidly protects tuataras to
ensure the continued existence of this species, a living
relic of an ancient world.

by Richard Essex Barwick, M.SC.(N.Z.),
Lecturer, Zoology Department, School of General Studies,
Australian National University, Canberra, A.C.T.

Co-creator

Richard Essex Barwick, M.SC.(N.Z.), Lecturer, Zoology Department, School of General Studies, Australian National University, Canberra, A.C.T.

How to cite this page: 'TUATARA', from An Encyclopaedia of New Zealand, edited by A. H. McLintock, originally published in 1966.Te Ara - the Encyclopedia of New ZealandURL: http://www.TeAra.govt.nz/en/1966/tuatara (accessed 20 Nov 2018)